|From:||Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>|
|To:||David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>|
|Cc:||"Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com>, "pgsql-hackers(at)lists(dot)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org>|
|Subject:||Re: Speed up transaction completion faster after many relations are accessed in a transaction|
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David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> writes:
> On Tue, 19 Feb 2019 at 12:42, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> My own thought about how to improve this situation was just to destroy
>> and recreate LockMethodLocalHash at transaction end (or start)
>> if its size exceeded $some-value. Leaving it permanently bloated seems
>> like possibly a bad idea, even if we get rid of all the hash_seq_searches
>> on it.
> That seems like a good idea. Although, it would be good to know that
> it didn't add too much overhead dropping and recreating the table when
> every transaction happened to obtain more locks than $some-value. If
> it did, then maybe we could track the average locks per of recent
> transactions and just ditch the table after the locks are released if
> the locks held by the last transaction exceeded the average *
> 1.something. No need to go near shared memory to do that.
Yeah, I'd deliberately avoided saying how we'd choose $some-value ;-).
Making it adaptive might not be a bad plan.
regards, tom lane
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